蚯蚓和秸秆对铜污染土壤微生物类群和活性的影响

试验设置4个Cu浓度水平：0、100、200和400 mg·kg^-1 Cu²⁺，每个Cu浓度水平设置4个处理：对照(CK)、表施秸秆(M)、接种蚯蚓(E)、同时加入蚯蚓和秸秆(ME)，研究了在Cu污染土壤中加入蚯蚓和秸秆对土壤微生物数量及活性的影响.结果表明：Cu污染、秸秆和蚯蚓均明显影响土壤微生物类群; Cu污染对细菌、放线菌具有抑制作用，而对真菌没有影响；秸秆显著提高了真菌数量；蚯蚓使土壤细菌、放线菌数量显著增加，而对真菌数量影响不大.Cu污染浓度＞200 mg·kg^-1处理对微生物量碳具有抑制作用；加入秸秆或蚯蚓，可显著提高土壤微生物量碳，而且同时加蚯蚓和秸秆处理土壤微生物量碳增加最显著.加入蚯蚓和秸秆后，土壤呼吸值显著增高.Cu<200 mg·kg^-1时，蚯蚓处理土壤呼吸值最大，平均比对照高3.06～5.58倍；Cu≥200mg·kg^-1时，蚯蚓、秸秆同时加入处理土壤呼吸值最高.4个处理土壤代谢商大小顺序为：ME>E>M>CK.蚯蚓和秸秆处理对土壤NH₄⁺-N没有影响，而对土壤NO₃^--N影响各异.接种蚯蚓，可显著提高土壤NO₃^--N含量；加入秸秆，可显著降低土壤NO₃^--N含量；同时加入蚯蚓和秸秆处理NO₃^--N含量最低.相关分析表明，土壤有效态Cu(DTPA-Cu)与土壤放线菌、细菌呈显著负相关，而与土壤呼吸、土壤NO₃^--N、NH₄⁺-N含量呈显著正相关.引入秸秆和蚯蚓，可在一定程度上减缓Cu污染对微生物数量和活性的影响.

Effects of earthworm inoculation and straw amendment on soil microflora and microbial activity in Cu contaminated soil.

In this paper, the dynamics of microflora and microbial activity in soil added with 0, 100, 200 and 400 mg x kg(-1) of Cu2+ were studied under effects of inoculating earthworm and applying straw. Four treatments were installed, i.e., CK, surface application of straw (M), inoculation of earthworm (E), and M plus E (ME). The results showed that Cu contamination had inhibitory effect on soil bacteria and actinomycetes, but no effect on soil fungi. Straw amendment increased soil fungi significantly, while earthworm inoculation could increase the numbers of soil bacteria and actinomycetes significantly but had little effect on soil fungi. When the Cu concentration was higher than 200 mg x kg(-1, soil microbial biomass carbon was depressed, but earthworm inoculation and straw amendment could enhance it, with most significant effect under the combination of these two treatments. Earthworm inoculation and straw amendment could enhance soil basal respiration markedly. When the Cu concentration was lower than 200 mg x kg(-1), treatment M had the highest soil basal respiration, being about 3.06-5.58 times higher than that of CK, while at Cu > or =200 mg x kg(-1), soil qCO2 followed the sequence of ME > E > M > CK. Treatments M and E had no effects on soil NH4+ -N. As for soil NO3- -N, treatment E could increase it significantly, but treatment M was in adverse. Treatment ME induced the lowest soil NO3- -N. In a definite degree, earthworm inoculation and straw amendment could mitigate the negative impact of Cu contamination on soil microflora and microbial activity.